oxygen-gas-o2-is-very-reactive-while-argon-gas-is-inert-but-why-do-both-oxygen-g

Question

Oxygen gas, O_{2}, is very reactive while argon gas is inert. But why do both oxygen gas and argon gas have zero standard enthalpies of formation?

Accepted Answer

Because oxygen gas and argon gas are both standard states of pure elements, their standard enthalpy of formation is zero.

Answer

Because oxygen gas and argon gas are both gases of pure elements, their standard enthalpy of formation is zero.

Answer

Because oxygen gas and argon gas are both reactive substances of pure elements, their standard enthalpy of formation is zero.

Answer

Because oxygen gas and argon gas are both non-reactive substances of pure elements, their standard enthalpy of formation is zero.

Oxygen gas, O2, is very reactive while argon gas is inert. But why do both oxygen gas and argon gas have zero standard enthalpies of formation?